California’s Largest Wildfire on Record is 100-Percent Contained

The Thomas fire started Dec. 4 in Ventura County and scorched nearly 282,000 acres as it marched into Santa Barbara County

By Jonathan Lloyd •Published January 12, 2018•Updated on January 12, 2018 at 6:36 pm

The largest wildfire on record in California is 100 percent contained more than a month after it began in the hills of Ventura County, according to Los Padres National Forest officials.

The nearly 282,000-acre Thomas fire spread into Santa Barbara County, burning homes and charring hillsides -- a chain of events that eventually led to this week's deadly mudflows in Montecito. Authorities made the determination after flights Thursday over the burn area, marking an important milestone after weeks of grueling work by firefighters to protect lives and property.

A wildfire is contained when it is surrounded on all sides by some type of boundary, but is still burning and could jump one of those boundaries. When there is no further threat of a fire jumping a containment line, it's considered controlled -- at that point, the fire fight is over.

An official cause of the fire, which began Dec. 4, has not been determined.

Two deaths were reported in connection with the fire, which was driven by strong winds. Firefighter Cory Iverson, 32, died due to thermal injuries and smoke inhalation, according to the medical examiner. A 70-year-old woman was killed in a car crash along an evacuation route.

The fire destroyed more than 1,060 structures.

It also stripped brush from hillsides above Montecito. Without vegetation, soil does not absorb enough rain, causing water to bounce of the surface and flow downhill.

It was one of several devastating wildfires that burned throughout California last year. Cal Fire's analysis of 2017 showed that five of the top 20 most destructive fires in the state's history occurred last year.

In 2017, there were 7,117 fires recorded within the Cal Fire jurisdiction, which burned 505,956 acres. This is nearly double what was reported in 2016. In 2016, Cal Fire recorded 4,800 fires, totaling 244,319 acres burned.

The year-end tally does not include the Thomas fire.

The state historically faces an increased wildfire threat in fall, but dry and windy conditions persisted into December last year. The Thomas fire's size and rate of spread would be considered significant at any time of year, but it is unprecedented for December and January.

The significant increase in the numbers and size of fires was largely because the state was coming off one of its wettest winters in years in 2016-2017, which left hillsides covered in grass and other vegetation. That grass dried out in summer and turned into tinder, providing fuel for rapidly spreading fires often pushed by strong winds that can carry hot embers for miles and turn small spot fires into infernos.